Cliff and Olivia met back in 1971 when she became a regualr guest singer on his variety show, and she even joined him on tour as a backing singer.
The music legend has previously admitted he 'fell in love' with the Grease star, but 'lost his chance' because she was engaged to someone else.
Speaking in his autobiography The Dreamer, he said: 'We hit it off straight away. She was the sort of soulmate that you meet and you know is a friend for life.
Celebrity tour bus crashes and other drama
Whenever a celebrity is involved in a plane crash, it makes the headlines. Plane accidents tend to receive their fair share of media attention largely because they are so devastating. Bus crashes, on the other hand, receive remarkably little attention by comparison, despite the fact that they can be equally as terrible. Jewel's tour bus didn't crash but it did catch fire, the famed singer-songwriter revealed to her fans. The bus went up in flames while parked at a hotel, but luckily no one was injured and firefighters were able to put out the blaze quickly. “We had a full bus fire," Jewel revealed on her TikTok. "Nobody was hurt, it happened on an off day, in the parking lot of a hotel. The fire department came, everybody is safe, we saved the vintage guitar and guitar amp… All’s well that ends well, but how about this bulls—?” The footage showed the extent of the fire damage on the bus, which Jewel has been taking along on tour for her 13th studio album, 'Freewheelin' Woman.' Check out this gallery to learn about some celebrity tour bus crashes and other bus drama involving stars.
'When I and many of us were in love with Olivia she was engaged to someone else. I'm afraid I lost the chance.'
Tributes have poured in for Olivia since her passing was announced on Monday, lead by her Grease co-star John Travolta.
Goldie Hawn pays powerful tribute to Olivia Newton-John alongside all-star throwback video
Goldie Hawn broke her social media silence to pay a heartbreaking tribute following the death of Olivia Newton-JohnMORE: Goldie Hawn shows support for famous daughter-in-law as she undergoes major transformation
On Tuesday Didi Conn revealed Olivia opened up to her about her ailing health when they spoke 'a couple of weeks ago.'
The star was first diagnosed with breast cancer in 1992, but the disease returned in 2013 and in 2017.
'She told me that her health was, you know, she wasn't walking anymore and she had full-time care but her husband John and her daughter Chloe were there all the time, and she told me that they were just so hopelessly devoted,' she said on Good Morning America.